diff options
| -rw-r--r-- | sys/boot/i386/btx/btx/btx.S | 24 |
1 files changed, 18 insertions, 6 deletions
diff --git a/sys/boot/i386/btx/btx/btx.S b/sys/boot/i386/btx/btx/btx.S index f7d848f3fbe1..569ba9d5fb55 100644 --- a/sys/boot/i386/btx/btx/btx.S +++ b/sys/boot/i386/btx/btx/btx.S @@ -493,9 +493,7 @@ v86mon.3: cmpb $0xf,%al # Prefixed instruction? je v86wrmsr # Yes cmpb $0x32,(%esi) # Is it a RDMSR? je v86rdmsr # Yes - cmpb $0x20,(%esi) # Is this a - jne v86mon.4 # MOV EAX,CR0 - cmpb $0xc0,0x1(%esi) # instruction? + cmpb $0x20,(%esi) # Is this a MOV reg,CRx? je v86mov # Yes v86mon.4: cmpb $0xfa,%al # CLI? je v86cli # Yes @@ -527,10 +525,24 @@ v86mon.7: subl %edi,%esi # From linear leal 0x8(%esp,1),%esp # Discard int no, error iret # To V86 mode /* - * Emulate MOV EAX,CR0. + * Emulate MOV reg,CRx. */ -v86mov: movl %cr0,%eax # CR0 to - movl %eax,0x1c(%ebp) # saved EAX +v86mov: movb 0x1(%esi),%bl # Fetch Mod R/M byte + testb $0x10,%bl # Read CR2 or CR3? + jnz v86mov.1 # Yes + movl %cr0,%eax # Read CR0 + testb $0x20,%bl # Read CR4 instead? + jz v86mov.2 # No + movl %cr4,%eax # Read CR4 + jmp v86mov.2 +v86mov.1: movl %cr2,%eax # Read CR2 + testb $0x08,%bl # Read CR3 instead? + jz v86mov.2 # No + movl %cr3,%eax # Read CR3 +v86mov.2: andl $0x7,%ebx # Compute offset in + shl $2,%ebx # frame of destination + neg %ebx # register + movl %eax,0x1c(%ebp,%ebx,1) # Store CR to reg incl %esi # Adjust IP /* * Return from emulating a 0x0f prefixed instruction |